feat(tool): use go.mod for -module

tool/cmd/kitex/args/args.go

@@ -16,11 +16,13 @@ package args
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
+	"path"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -270,50 +272,74 @@ func (a *Arguments) checkStreamX() error {
 	return nil
 }
 
-func (a *Arguments) checkPath(curpath string) error {
-	pathToGo, err := exec.LookPath("go")
+// refGoSrcPath returns ref path to curpath, base path is $GOPATH/src
+func refGoSrcPath(curpath string) (string, bool) {
+	gopath, err := util.GetGOPATH()
 	if err != nil {
-		return err
+		return "", false
 	}
-
-	gopath, err := util.GetGOPATH()
+	gosrc, err := filepath.Abs(filepath.Join(gopath, "src"))
 	if err != nil {
-		return err
+		return "", false
+	}
+	// if curpath is NOT under gosrc
+	if !strings.HasPrefix(curpath, gosrc) {
+		return "", false
 	}
-	gosrc := util.JoinPath(gopath, "src")
-	gosrc, err = filepath.Abs(gosrc)
+	ret, err := filepath.Rel(gosrc, curpath)
 	if err != nil {
-		return fmt.Errorf("get GOPATH/src path failed: %s", err.Error())
+		return "", false
 	}
+	return ret, true
+}
 
-	if strings.HasPrefix(curpath, gosrc) {
-		if a.PackagePrefix, err = filepath.Rel(gosrc, curpath); err != nil {
-			return fmt.Errorf("get GOPATH/src relpath failed: %s", err.Error())
-		}
-		a.PackagePrefix = util.JoinPath(a.PackagePrefix, a.GenPath)
-	} else {
-		if a.ModuleName == "" {
-			return fmt.Errorf("outside of $GOPATH. Please specify a module name with the '-module' flag")
+func (a *Arguments) checkPath(curpath string) error {
+	genPath := filepath.ToSlash(a.GenPath) // for PackagePrefix
+	usingGOPATH := false
+
+	// Try to get ref path to $GOPARH/src for PackagePrefix
+	// Deprecated: to be removed in the future
+	if ref, ok := refGoSrcPath(curpath); ok {
+		usingGOPATH = true
+		a.PackagePrefix = path.Join(filepath.ToSlash(ref), genPath)
+	}
+
+	goMod, goModPath, hasGoMod := util.SearchGoMod(curpath)
+	if usingGOPATH && a.ModuleName == "" && !hasGoMod {
+		log.Warn("You're relying on $GOPATH for generating code.\n" +
+			"Please add go.mod or specify -module for module path.\n" +
+			"We will deprecate $GOPATH support in the near future!")
+	}
+
+	if !usingGOPATH && a.ModuleName == "" {
+		// try to update a.ModuleName with module name from go.mod
+		if hasGoMod {
+			a.ModuleName = goMod
+		} else {
+			// case:
+			// * -module not set
+			// * not under $GOPATH/src
+			// * go.mod not found
+			return errors.New("Please specify a module name with the '-module' flag")
 		}
 	}
 
 	if a.ModuleName != "" {
-		module, path, ok := util.SearchGoMod(curpath)
-		if ok {
-			// go.mod exists
-			if module != a.ModuleName {
+		if hasGoMod {
+			if goMod != a.ModuleName {
 				return fmt.Errorf("the module name given by the '-module' option ('%s') is not consist with the name defined in go.mod ('%s' from %s)",
-					a.ModuleName, module, path)
+					a.ModuleName, goMod, goModPath)
 			}
-			if a.PackagePrefix, err = filepath.Rel(path, curpath); err != nil {
-				return fmt.Errorf("get package prefix failed: %s", err.Error())
+			refPath, err := filepath.Rel(goModPath, curpath)
+			if err != nil {
+				return fmt.Errorf("get package prefix failed: %w", err)
 			}
-			a.PackagePrefix = util.JoinPath(a.ModuleName, a.PackagePrefix, a.GenPath)
+			a.PackagePrefix = path.Join(a.ModuleName, filepath.ToSlash(refPath), genPath)
 		} else {
-			if err = initGoMod(pathToGo, a.ModuleName); err != nil {
-				return fmt.Errorf("init go mod failed: %s", err.Error())
+			if err := initGoMod(a.ModuleName); err != nil {
+				return fmt.Errorf("init go mod failed: %w", err)
 			}
-			a.PackagePrefix = util.JoinPath(a.ModuleName, a.GenPath)
+			a.PackagePrefix = path.Join(a.ModuleName, genPath)
 		}
 	}
 
@@ -541,11 +567,14 @@ func LookupTool(idlType, compilerPath string) string {
 	return path
 }
 
-func initGoMod(pathToGo, module string) error {
+func initGoMod(module string) error {
 	if util.Exists("go.mod") {
 		return nil
 	}
-
+	pathToGo, err := exec.LookPath("go")
+	if err != nil {
+		return err
+	}
 	cmd := &exec.Cmd{
 		Path:   pathToGo,
 		Args:   []string{"go", "mod", "init", module},